Ultrasound has long been used for diagnostic imaging applications. More recently however, several new therapeutic applications for ultrasound are being discovered. Ultrasound therapy typically uses an ultrasound transducer to radiate acoustic energy to a treatment region. Ultrasound transducers typically comprise at least one transduction element configured to focus or defocus acoustic energy. To suitably focus or defocus acoustic energy to a treatment region, the geometry of the ultrasound transduction element(s) is adjustably configured (e.g., concave, convex, and/or planar). Alternatively, or additionally, ultrasound transducers may comprise one or more adjustably configured lenses to appropriately focus or defocus acoustic energy.
Because acoustic energy is poorly transmitted through air, it is important that it be effectively coupled to the treatment region and that the couple is acoustically transparent. To achieve acoustic transparency, the couple is typically similar in acoustic properties to the cells and/or tissues within the treatment region. Typically, a fluid or a gel is used as the couple, with such fluid or gel spread along the outer surface, such as the epidermis layer, in between the transducer probe and the outer surface to facilitate acoustic coupling.